双侧关节突关节切除诱发椎间盘退变的磁共振计量分析

Quantitative MRI analysis of intervertebral disk degeneration caused by bilateral zygapophysial joint destruction

[目的]探讨新西兰大白兔腰椎关节突关节破坏诱发出椎间盘退变的核磁共振改变。[方法]30只新西兰大白兔,体重2.25~2.95kg,雄性。随机分为骨性手术组和软组织手术组。软组织手术组仅骨膜下剥离L3~7的椎旁肌肉;骨性手术组完整切除L4、5双侧下关节突和L5棘突,保留L5、L6上关节突。骨性手术组L4、5、L5、6椎间盘为实验组椎间盘,上下相邻的L3、4、L6、7为自身对照组椎间盘。软组织手术组L4、5、L5、6椎间盘为实验对照组椎间盘。术后1、2、4及8个月行核磁共振检查。将实验所得的L3、4、L4、5、L5、6、L6、7T2WI轴位像输入电脑,用KONTRONIBAS2.0全自动图像分析系统分析图像中高信号区域面积占整个椎间盘面积的百分比（面积分数）并进行统计分析。[结果]新西兰大白兔T2WI矢状位像上,髓核呈均一高信号。T2WI轴位像上,髓核高信号区域位于椎间盘中央,占椎间盘横截面积50%左右。养殖1个月与8个月面积分数比较无统计学差异。随着术后时间延长,实验组椎间盘轴位像上面积分数变化显著,自身对照组次之,实验对照组最小,相同时间3组之间比较有统计学差异,相同组别术后不同时间比较有统计学差异。[结论]脊柱失稳可以诱发椎间盘退变。髓核T2WI轴位像上面积分数减小能够较早反映出椎间盘退变。

[ Objective] To study the MRI changes in rabbit lumbar intervertebral disk degeneration induced by spinal intervertebral instability through destroying L4,5 and L5,6 zygapophysial joints. [ Method ] Thirty male New-Zealand rabbits were randomly divided into operation group on the bone and operation group on the soft tissue. In operation group on the bone, L4 and Ls inferior articular processes were en bloc excised, Ls and L6 superior articular processes were retained. In the operation group on the soft-tissue, Only L3 to L7 paravertebral muscles were stripped. In operation group on the bone, L4,5 and L5,6 intervertebral disks were acted as experimental group; L3,4 and L6,7 acted as self-control group. In the operation on the soft tissue, L4,5 and L5,6 were acted as experimental control group. One, two, four and eight months post-operation, lumbar spine MRI of New-Zeal- and rabbits were performed. The area fractions of high T2 signal zone of the nucleus pulposus were calculated according to the ref- erence reports. [ Reset] On the T2 sagittal image, the nucleus pulposus showed uniform high signal intensity. On the axial image, high signal area of the nucleus pulposus located at the center of the intervertebral disk, and the areal fraction was 50% . High sagittal T2 signal and area fraction of high axis T2 signal of the nucleus pulposus not obviously declined in the normal rab-bit with time. There was no statistical difference by t test. However, MRI showed the most significantly decreased the axial T2 high-signal area fraction in the experimental group, and the smallest declined in the experiment-control group. At the end of eight months after operation, L4,5 and L5,6 appeared the dark discs in the experiment group. [ Conclusion] Disc degeneration may be caused by spine instabili-ty. The decline of the axial T2 high-signal area fraction of the nucleus pulposus is a earlier and common sign of intervertebral disk degeneration.